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Oct 08, 2023

How a greywater system can help Berkeley homeowners

As we collectively hope for more winter rains, it’s a perfect time to think about greywater. A previous version of this story was first published on Edible East Bay This is the gently used water from

As we collectively hope for more winter rains, it’s a perfect time to think about greywater.

A previous version of this story was first published on Edible East Bay

This is the gently used water from washing machines, bathroom faucets, showers, and bathtubs — but not toilets — that can be captured, filtered and reused. California residents have the option of installing greywater systems in their own homes, thanks in no small part to environmental activists who built an illegal greywater system at Berkeley’s EcoHouse in 2004.

“They went ahead and just put one in,” said Martin Bourque, director of the Ecology Center, which operates the EcoHouse. The model home and garden, created in 1999 by community activists and located on Hopkins Street, is intended to demonstrate accessible, affordable ways of ecological living. It was developed by activists involved in community gardens, including landscape architect Karl Linn and general contractor B. Mano Tondre.

The greywater system consisted of gravel and wetland plants with deep, woven root systems to filter the home’s water and the activists estimated it saved as much as 27,000 gallons per year. But after a greywater workshop was held at the EcoHouse in 2004, city inspectors told the activists that the home was not up to building codes around wastewater contamination.

“We got in a lot of trouble for that,” said Tondre, who went on to cofound DIG Cooperative, Inc., which designs and builds greywater and rainwater systems. “I said, ‘you know what, I’m going to get a permit; I’m going to make good where we failed.’”

In January 2007, after more than a year of back-and-forth between the activists and the city’s building department, the revamped system at EcoHouse became “the first permitted greywater system of its type for small residential homes that we know of in California,” Bourque said.

The process helped pave the way for changes in the plumbing code in 2009 that made it much easier to build simple, low-cost non-potable water systems legally. Santa Barbara had redefined greywater as distinct from blackwater in 1989, and California began legalizing greywater systems in the early 1990s but rules were initially too restrictive to make installing the systems practical.

In his work at DIG Cooperative, Tondre has seen the popularity of greywater increasing in recent years as people invest in their homes to address climate change and drought. A few U.S. cities such as Tucson even mandate builders to include piping for greywater recycling in new homes.

The benefits of greywater extend far beyond the obvious advantages of saving water in drought-prone areas and spending less on water bills. When greywater is reused, it keeps the water out of sewer and septic systems, reducing the strain on those systems and the likelihood of polluting local bodies of water. Today, simple, low-cost greywater systems that don’t require plumbing changes can be installed without a construction permit.

Laura Allen, who led greywater workshops at EcoHouse, went on to become a founding member of Greywater Action, a Bay Area educational collaborative that teaches residents and tradespeople how to reduce household water use.

She encourages people interested in greywater systems to start by figuring out which portion of their landscape they can irrigate with water from their washing machines. This Laundry to Landscape (L2L) method was invented in 2008 by author and ecological systems designer Art Ludwig.

See resources recommended by the Ecology Center for building greywater and rainwater catchment systems

Allen has plenty of practical advice for those who want to install such a system.

“Look at your landscape and start with your biggest plants, the trees; they’re easiest to get the water to,” she says. “Greywater is excellent for fruit trees, shrubs, berries, and other large plants, but shouldn’t be used on edibles if it would directly touch the food part, for example, a carrot.”

In her Alameda home, Ayse Sercan started out in 2008 with a simple L2L system, which draws on water from the outlet hose at the back of the washing machine and doesn’t require a special tank or filter. When Sercan was training as an architect, she says the topic of greywater came up frequently. “We talked about the fact that we waste a lot of water that’s perfectly usable just because it’s a little bit used,” she says. “I wanted to see what the benefits of greywater could be, and I was willing to experiment on my own house.”

As Sercan’s washing machine pumps water out (most pump between seven and 26 gallons per load, according to Consumer Reports), a diverter valve directs the water either down the drain to the sewer system or out to the landscape. For each load of laundry, a resident can decide where they want the water to go, selecting the sewer option if, for example, they’re using bleach in the wash.

Water headed for the garden flows through greywater tubing into underground mulch basins (aka swales) dug near trees or large plants. At Sercan’s home, this includes a thriving array of mulberry, plum, Asian pear, apricot, cherry, and citrus. The mulch basins serve as filters that trap particles of lint or soap as the greywater soaks down around the roots of the plants.

“On the residential level, you have control over what goes down the drain, and that impacts the quality of the water,” says Allen.

Products to avoid sending into the garden include powdered laundry detergent and detergents containing salt, boron, or chlorine bleach. Because greywater contains organic matter, it should be used promptly, not stored or allowed to run out to storm drains, which lead to streams and creeks headed to the San Francisco Bay.

More complex systems can capture greywater from bathtubs, showers, and bathroom sinks in addition to washing machines and guide it to multiple zones within larger gardens.

In 2017, Sercan’s home was replumbed, and she’s currently having Oakland-based cooperative Mariposa Gardening & Design install one of their “living fountain” greywater systems. Unlike a simple L2L system, this design includes a circulating pump that helps the plants and soil filter the water via their naturally occurring bacteria.

“There is no better way to clean water than through plant roots and soil,” says Andrea Hurd, Mariposa’s lead designer and stonemason. “The living fountain also allows you to grow plants that increase the biodiversity in your garden. Because the system is self-contained and there’s always water filtering through it, you can also grow wetland plants. When we’re thinking about drought-tolerant gardening, we eliminate this whole body of plant life that is also good for the planet and for pollinators.”

Unlike untreated greywater, the water filtered through a living fountain has enough impurities removed to run it through a drip irrigation system.

Innovations in systems for larger homes and businesses include the Hydraloop, which looks like a high-tech refrigerator. Developed in the Netherlands, it collects and cleans greywater from multiple sources and moves the disinfected water to toilets for flushing, to washing machines for laundry, and to irrigation or pools. Costs for the basic unit start at about $6,000, not including plumbing, installation and consulting costs.

Paul Mann, CEO of the consulting and design business Water Champions, has installed Hydraloops in Marin and the East Bay.

“Any system that reduces your water use and helps to keep your landscape green and fire resistant is a good investment right now,” says Mann. “As climate change and extreme drought continue to impact our supply and availability of water, we will all need to conserve to make what water we have left go farther.”

Mann was able to reduce his own municipal water consumption by 68% by using greywater from laundry, sinks, showers, and tubs, as well as rainwater collected from the roof, a $50 leak-detection device, and a $70 smart irrigation controller.

“Greywater and rainwater belong together,” says Elizabeth Dougherty, whose East Bay nonprofit, Wholly H2O, gets people out into watersheds and uses citizen science, art and education to build motivation for responsible water use.

“It’s not just reusing water, but how much water you use,” says Dougherty. Shorter showers, less flushing of toilets, and mindfulness at the kitchen sink are all easy ways to cut back. “I’m thinking about my ecosystem neighbors and other living creatures every time I turn on my tap in Oakland,” she says.

A lot of rain isn’t a requirement for collecting substantial amounts of rainwater. One inch of rainfall on a 1,000-square-foot roof can yield 600 gallons, which runs from downspouts or pipes into barrels, cisterns, or other rainwater tanks. These containers should be dark to help prevent algae from growing and covered by a screen to keep leaves and bugs out. Rainwater vessels can range from small barrels to huge tanks storing thousands of gallons.

A variation is the rain garden, where sunken beds might host native and drought-tolerant plants. The beds take advantage of gravity as they capture runoff from hard surfaces like roofs, driveways, or streets. A rain garden reduces the pollutants that would otherwise run into storm drains, lakes, and streams while also adding greenery without requiring irrigation. During large storms, a rain garden helps reduce flooding and erosion.

For people who like DIY projects, the cost of supplies for a basic L2L system is as little as $200–$400. Laura Allen recommends hiring a professional installer rather than buying a ready-made kit since each system should be customized to the particular setting. Professional installation might run $1,000–$2,000, depending on the size and setup of your home and garden.

According to the East Bay Municipal Utility District (EBMUD), an L2L system saves about 3,600 gallons a year if you have a water-efficient clothes washer and up to 11,200 gallons a year if you have an older top loader. In addition, some rebates are available: For example, EBMUD offers $50 for the purchase of a three-way diverter valve.

Given the grim realities of drought and climate change, perhaps your moment to “go grey” has arrived. “This is a great time for people who haven’t yet tapped into greywater to look at it and see if it works for them,” says Allen. “Droughts can be a good opportunity to shift how we’re doing things with our homes and landscapes to be more sustainable in the long run.”

Rachel Trachten writes about social justice, education, business, food and the environment. A version of this story was first published by Edible East Bay, which permitted the story to be republished out of belief in its great value to the community.

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Rachel Trachten writes about social justice, education, business, food and the environment. More by Rachel Trachten